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Full text of "The manufacture and properties of iron and steel"

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THE OPEN-HEARTH FURNACE.                             151
in the hot gases or by radiation and conduction. These losses are definite losses. The total calorific power of the coal is the calorific power of the gases produced, plus the definite losses of heat from the producer, as just defined. The proportion these losses bear to the total calorific power of the coal is the percentage of producer loss.
Von Jiiptner used no steam jet, and, therefore had little decomposition of steam in his producer. He, however, calculates the total calorific value of the coal by adding together the calorific power of the gases and the total heat created in the producer, including, moreover, in the latter item the heat of combustion of the hydrogen of the coal which goes into the gases as water. Aside from the fact that he uses the calorific power of hydrogen to liquid water, wrongly including the irrecoverable heat of vaporization of steam, the above calculation of- the total calorific power of the coal contains two erroneous items, viz.: (1) any heat rendered latent in the producer by decomposition of steam is counted twice, once in the heat developed in the producer, and the second time in the calorific power of the gas. This item is small in this particular case, but is considerable in the Steelton producers. (2) Including the heat of formation of the water in the gas coming from the combination of hydrogen of the coal with oxygen in the coal is practically assuming that all the H of the coal is free to burn, and neglects the principle of "available hydrogen" or "hydrogen free to burn." The calorific power of the coal is thus increased by this quantity more than the power of the coal can really be, and the surplus thus found above the experimentally ascertained calorific power of the coal is called by von Jiiptner the "heat of gasification" (Vergasungswarme) of the coal. This is entirely a hypothetical quantity which has no place in the calculations in theory and no existence in practice.
Von Jiiptner is also in error in using 0° C. as a basis, for this is an arbitrary point having no relation to the problem. It would be as logical to use —10.000° C.. but if we did so the heat brought into the furnace by gas and air and stock would be in excess of the heat produced by combustion—an answer quite correct theoretically, but absurd practically. The proper datum is the average temperature of the stock, gas and air entering the valves.
The wovking of the producer is shown in Table VIII-C.   Von